Synthesis, band structure and photocatalytic properties of Sillen-Aurivillius oxychlorides BaBi5Ti3O14Cl, Ba2Bi5Ti4O17Cl and Ba3Bi5Ti5O20Cl with triple-, quadruple- and quintuple-perovskite layers

Sillen-Aurivillius layered oxyhalides with single-, double- and triple-perovskite slabs (n = 1-3) are promising visible-light-driven photocatalysts for water splitting with different behaviors observed depending on n. However, there was no report on the photocatalytic activity of n >= 4 phases. Here, we report three new oxychlorides BaBi5Ti3O14Cl, Ba2Bi5Ti4O17Cl and Ba3Bi5Ti5O20Cl, respectively, with triple-, quadruple- and quintuple-perovskite layers. The synthesis of these phases involves a bricklaying synthesis, where a plain perovskite, BaTiO3, a Sillen phase, BaBiO2Cl, and Aurivillius phases Bi4Ti3O12, BaBi4Ti4O15, and Ba2Bi4Ti5O18 were used as building blocks. The present Sillen-Aurivillius oxychlorides have appropriate valence and conduction band levels for visible-light-induced water splitting. DFT calculation for BaBi5Ti3O14Cl (n = 3) and Ba3Bi5Ti5O20Cl (n = 5) indicates that their valence and conduction bands are separated spatially on the perovskite and fluorite layers, respectively. The photocatalytic activity of the three Sillen-Aurivillius oxychlorides is enhanced with increasing the number of the perovskite layers.

Automated summary

This study reported three new oxychlorides with enhanced photocatalytic activity as the number of perovskite layers increased.